Tuatara

Fast facts

Adults are between 30 and 75 centimetres long, and weigh between 250 and 1,200 grams.

Males are larger than females.Photo: Craig Potton

The tuatara is famous because it is the only survivor of an ancient group of reptiles that roamed the earth at the same time as dinosaurs. It hasn't changed much in over 225 million years! The relatives of tuatara died out about 60 million years ago which is why the tuatara is called a ‘living fossil’.

Know your tuatara

Tuatara once lived throughout the mainland of New Zealand but rats and people drove them to extinction there. They are now found only on 37 off-shore islands and mainland islands like the Karori Sanctuary. Total tuatara population on all these islands is estimated to be between 50,000 and 100,000.

There are two species. Sphenodon punctatus is the Cook Strait tuatara which live on Stephen's Island in the Marlborough Sounds.

The Northern tuatara, Sphenodon punctatus punctatus, is a sub-species which live on offshore islands around the north of the North Island.

There are much fewer of the second species, Sphenodon guntheri, Brother's Island tuatara. They are slightly smaller than the other tuatara and lived ONLY in a patch of scrub on the top of tiny North Brother Island in the Marlborough Sounds.

To help the population grow and keep them safer from extinction, some Brother’s Island tuatara have been taken to other, rat-free islands including Matiu/ Somes Island in Wellington harbour.

The life of tuatara

The male tuatara is bigger than the female and has a more prominent crest of spines along its back. They both become sexually mature when they are 15 to 20 years old.

Having babies is a slow process…

Only once every two to five years will the female be ready to mate. The male will sit outside her burrow and wait. If she is interested they will mate and 8 or 9 months later she will lay and bury 6 to10 eggs in a sunny place. 11 to 16 months later the baby tuatara will hatch.

Here’s the really interesting part. The warmer the soil around the eggs, the greater the chance they will hatch into males and the cooler the soil, the greater the chance that they will hatch into females – what a cool discovery! Scientists at Victoria University found that at 22° C, 80% of tuatara incubated would hatch into males, at 20° C, 80% were likely to be females and at 18° C, all the tuatara hatched were female.

Climate change

If our earth warms, as climate change scientists predict then all of the tuatara that hatch will be male! These male tuatara won't be able to find mates, and that means they won't be able to have babies. Our tuatara will be snuffed out!

Home: island & mainland sanctuaries

Tuatara used to live on mainland New Zealand but, like many other endangered species, they breed too slowly to keep up with the death rate caused by predators and people. That’s why they are now only found on offshore islands and mainland sanctuaries where there are no introduced predators (especially rats) and where people look after them.

Weird and wonderful facts about tuatara

• They can hold their breath for an hour! • They grow very slowly and only stop growing when they are 35 years old.• They can live to be over 100 years old. • Like other reptiles, tuatara are cold-blooded, which means their temperatures change with the air temperature. The scientific name for cold-blooded is ‘poikilothermic’.• Tuatara are nocturnal and prefer cool weather. However they will often bask in the sun to warm their bodies – but they are careful not to over-heat. • On warm nights they come out to hunt for food – mainly insects, lizards and seabird eggs and chicks. • Young tuatara hunt for food during the day – to avoid being eaten by adult tuatara at night! • The colour of tuatara ranges from olive green to brown to orange-red, and they can change colour over their lifetime • They shed their skin once a year • They often live in old burrows previously dug by seabirds but they aren’t likely to share with the birds. A tuatara might bite off a baby bird’s head if it is hungry – which doesn’t make it a very good house guest! • Tuatara use their ‘egg tooth’, a spike on the end of their snout, to break out of their egg. The ‘egg tooth’ will fall off during the first three weeks of life. • The male has a distinctive crest of spines running along the neck and down the back which he can fan out to attract females or when fighting with other males. • Tuatara are amazing creatures. If we protect them they will survive and not become extinct.